A senior Iranian commander says the country has reverse-engineered an American spy drone captured by Tehran’s armed forces last year and has begun building a copy.

General Amir Ali Hajizadeh, who is chief of the aerospace division of the powerful Revolutionary Guards, was quoted Sunday by the semi-official Mehr news agency as saying that experts are also recovering data from the U.S. RQ-170 Sentinel captured in December in eastern Iran.

Gen. Hajizadeh and revealed what he said were “codes” gleaned from the unmanned aircraft.

“I am giving you four codes so the Americans understand just how far we have gone in penetrating the drone’s secrets,” General Amir Ali Hajizadeh, the head of the Revolutionary Guards’ aerospatial division, told state television.

“In October 2010, the aircraft was sent to California for some technical issues, where it was repaired and after flight tests, it was taken to Kandahar (in Afghanistan) in November 2010, when a series of technical problems still prevailed,” he said.

“In December 2010, it was sent to an airport near Los Angeles for repair of its equipment and sensors, and flight tests. The drone was then sent back to Kandahar,” he said.

Hajizadeh did not give further details, saying: “This aircraft is a national treasure for us, and I cannot divulge information about it.”

But he added Iran has “started producing a copy of the RQ-170 drone,” stressing it used the same US technology in stealth fighters and bombers.

U.S. officials have said Iran will find it hard to exploit any data and technology aboard it because of measures taken to limit the intelligence value of drones operating over hostile territory.

Last December, the Iranian military’s electronic warfare unit announced that Iran had downed with minimal damage the U.S. RQ-170 Sentinel stealth reconnaissance aircraft, while it was flying above Iran’s Northeastern city of Kashmar. U.S. officials later confirmed that the drone was part of a CIA reconnaissance mission, involving the United States intelligence community stationed in Afghanistan.

According to the official Iranian news agency, reports from the Pentagon have revealed that United States’ military experts and officials are deeply worried about Tehran’s access to the drone as it contains highly classified technologies and materials which are used in a number of U.S. planes, including the F-22.

Meanwhile, Russia and China have asked Tehran to provide them with information on a U.S. drone, a senior Defense Ministry advisor said, according to the official FARS news agency on Saturday.

Ahmad Karimpour, an adviser to Iran’s defense minister, said Tehran has received requests from many countries for information on the RQ-170 Sentinel, but Moscow and Beijing have been most aggressive in their pursuit of details on the drone. He did not elaborate.